This invention concerns snowshoes and the manner in which snowshoes are secured to boots of users. Specifically the invention relates to use of a more effective, efficient and lower friction buckle used with a hole-punched rubbery strap of a snowshoe binding, as well as to a special design of buckle for general uses.
Snowshoes have some form of harness assembly for securely engaging a user""s boot, normally also including a strap to extend around the heel. Examples of snowshoe harness assemblies are shown in U.S. Pat. Nos. 5,440,827, 5,687,491, 5,699,630, 5,901,471 and copending application Ser. No. 10,199, filed Jan. 21, 1998 as well as copending application Ser. No. 494,324, filed Jan. 28, 2000.
A number of snowshoes have webbing type straps in the harness assemblies, formed of woven nylon, polyester or other synthetic fibers, often used with ladder lock type buckles to engage with the webbing strap to tighten the harness over a boot. Ladder lock buckles are based on a type of frictional engagement of the strap. Other buckles or latches have also been used, such as ratcheting buckles where movement of a lever in one direction advances the toothed strap by one tooth each stroke, and release is effected by an extreme movement of the lever. Such straps are relatively rigid. The latches are not as quick to use as ladder lock buckles, but greater leverage can be achieved in tensioning the harness.
Cam lock buckles are well known in contexts other than snowshoes, and in copending application Ser. No. 494,324 referenced above, a cam lock buckle of particular construction is described as used to secure the webbing straps on a snowshoe. The cam lock buckles have a generally nautilus-shaped hub, with varying radius and teeth located at the area of greatest radius. Typically the strap is doubled back over the same bar toward which the spring lever is biased, causing relatively high friction at this doubling over location, friction to be overcome when the strap is to be tightened. A positive grip on the strap is provided by the nautilus-shaped hub and the teeth, such that the greater the back-pulling force on the tensioned portion of the strap, the more the teeth engage into the strap and thus the more positive becomes the locking engagement.
Several snowshoes have used rubbery straps with a series of holes along the middle of the strap. These hole-punched straps (not necessarily formed by punching) are typically used with a buckle comprising a roughly rectangular frame having a fixed prong to engage in an appropriate strap hole when tightened.
It is an object of the invention described below to improve the ease of use and positive engagement with such a hole-punched strap on a snowshoe, through provision of an improved buckle for such a strap.
In this invention a snowshoe has a binding with straps, at least one of which is of the type with a series of holes down the middle of the strap. The strap or straps are fitted with at least one buckle which has a spring-loaded lever with a hub positioned to engage the strap between the hub and a wall of the buckle frame as the strap passes through the buckle in a looped back configuration. The hub of the buckle lever has a nipple or protrusion which is of a size to fit in any of the holes along the strap. The configuration of this buckle provides for ease of use, with low-friction pulling of the strap""s tail for tightening and with positive engagement of the strap, via the holes. This positive engagement is increased, in a manner similar to that of a cam lock buckle, as back-pulling on the tensioned part of the strap is increased. The increased back-pulling tension pulls against the nipple or protrusion in a manner that causes the spring loaded lever to close more tightly (in the same direction as spring force), thus further rotating the hub and lever and causing the protrusion to bite more deeply into the strap hole.
In a preferred embodiment of the lever, the outer end of the lever, which can be engaged by the thumb or finger of a user (but which action is usually not needed) has a downward bend that engages the strap tail and holds it down against the user""s boot, while also assisting in releasing the lever from the strap by reducing the angle at which the user needs to pull up on the strap to remove the nipple or protrusion from the strap holes.
It is thus a primary object of the invention to make simpler and easier the tightening and release of a tension strap passing through a buckle, and particularly in the context of snowshoes. This and other objects, advantages and features of the invention will be apparent from the following description of a preferred embodiment, considered along with the accompanying drawings.